Nowadays, DACs are required for converting digital signals to analog signals in various electronic products, such as communication systems. Current calibration and dynamic element matching (DEM) are the most commonly used for low-cost design. In the Institute of Electrical and Electronics Engineers (IEEE) published papers, the cost of the DEM technique is lower than that of the current calibration technique. Furthermore, the DEM technique may be applied for various technologies because the DEM encoder is implemented with digital circuits. The current calibration technique is limited for certain technologies because some of its building blocks are implemented with analog circuits.
In the DEM technique, inputs are rotated for generating specific outputs. The DEM technique comprises binary-weighted architectures, thermometer-coded architectures and algorithmic controller embedded architectures. The architectures with algorithmic controllers can be used to decrease the switching occurrence. However, the controller embedded architectures have more complicated designs which require more cost when implemented, and can't be operated in high-speed applications. The conventional binary-weighted architectures have advantages of low cost, low complexity, and low power consumption. However, when inputs approach the Nyquist frequency, the switching occurrence is greatly increased, so that glitch problems occur and the linearity is therefore affected. Accordingly, the conventional binary-weighted architectures are seldom used. Compared with the conventional binary-weighted architectures, the thermometer-coded architectures have a lower switching occurrence and can reduce noises. However, the thermometer-coded architectures must comprise additional control circuits, and thus the power consumption and the area cost are higher than those of the conventional binary-weighted architectures. Besides, the operation speed is limited.
Therefore, there is a need to propose a solution having the advantages of the binary-weighted architectures and the thermometer-coded architectures and not having the disadvantages of the binary-weighted architectures and the thermometer-coded architectures.